Tanker loading system



References Cited UNITED STATES PATENTS United States Patent Westmont, Illinois Application No.: 727,301 Filed:

r mh U0 SK 1 3 366088 1 1968 0b [22] May 7, 1968 3,366,982 2/1068 l 45 Patented: Aug. 4, 1970 3,404,654 10/1968 [73] Ass1gnee: Chicago Bridge & Iron Company Oak Brook Illinois Primary Examiner- Trygve M. BllX a Cor f Illi i A!t0rney-Merriam, Marshall, Shapiro and Klosc [54] TANKER LOADING SYSTEM 15 Claims, Drawing Figs.

114/230, ABSTRACT: A mooring system for vessels including a 9/8 mooring structure adapted for rotation about a fixed storage B63b 21/00 facility and including a first member spaced from and con- B63b 21/52 nected to a second member by damping means, the second [50] Field ofSearch........................................ 114/.5, member having forward and after booms offset from each other.

Patented Aug. 4, 1970 Sheet L of 4 Patented Aug. 4, 1970 3,522,787

Sheet 2 014 Ma s/v70? Patented Aug. 4, 1970 Sheet i I E U.S. PATENT3,522,787 TANKER LOADING SYSTEM This application relates to a mooring system for vessels such as tankers at locations including an offshore oil storage station and more particularly relates to a new and unobvious ship mooring structure and a method for mooring a ship.

The ability for a tanker or other ship to dock at an offshore location under adverse conditions is extremely important. It is known that a vast number of hours are lost annually because mooring structures and systems presently available are not adapted for receiving ships such as tankers in weather conditions other than optimum.

Moreover, even when weather conditions permit the mooring of a ship, present mooring systems are unsatisfactory due to their inability to damp impact loads caused by a tanker striking the mooring structure. Other systems, e.g. U. 5. Patent No. 3,245,438, disclose the mooring of a tanker directly to a fixed structure which requires a ship, in the process of mooring, to head directly toward the fixed storage tank or facility. This is undesirable as the damage which can be suffered by the storage facility due to some error or malfunction in mooring the tanker is readily apparent.

In order to obviate the deficiencies and disadvantages inherent in tanker mooring systems presently available, this invention provides a mooring structure and system for mooring a tankship in which the mooring structure is not rigidly attached to the storage structure but rather is adapted for 360 rotation. The mooring structure permits six degrees of freedom, i.e. heave, pitch, roll, sway, yaw and surge and provides for damping of impact loads caused by water action on a ship as it strikes the mooring structure. Moreover, in mooring a ship, it is not necessary for the ship to head directly toward the fixed storage tank but rather the ship heads toward a rotatably positioned target or pod on the mooring structure of the present invention.

The mooring structure of the present invention comprises a first member which is positioned about and contiguous to a fixed storage facility. A second member is positioned about and spaced from the first member and is connected to it by suitable damping means.

An after or first boom is joined to the second member and preferably at the outer end of the boom there is located an outboard or after pod having powered thruster means for providing radial orientation of the mooring structure about a fixed storage structure. A forward or second boom extends from the second member in a direction away from the after boom. A forward or second pod is located at the end of the forward boom furthest from the second member.

The forward and after booms are designed to permit the passage of oil or other liquid to a tanker and ballast water back to the structure.

In berthing a tanker, it is envisioned the mooring structure of the present invention will be rotated so that a specified distance, probably several hundred feet, between the ships motion and the center line of the fixed storage structure is maintained. Subsequently, running lines will be passed from a tanker to be moored to the forward pod of the mooring structure in addition to passing a line from theforward part of the ship to the after or outboard pod. The tanker will then be stopped dead in the water and a second line from the ship will be attached to the outboard pod.

The system of this invention permits tankers to approach the forward pod of the rotatable mooring structure, as opposed to heading directly for the storage tank as is the case with mooring systems disclosed in a number of patents such as U. S. Patent Nos. 3,155,069; 3,120,106 and 3,074,082. Further, as opposed to other mooring structures presently available which are submerged, the present invention is designed to float on the surface of the water.

Other features and advantages are inherent in the method and apparatus claimed and disclosed or will become apparent to those skilled in the art from the following detailed description in conjunction with the accompanying diagrammatical drawings wherein:

FIGURE 1 is a perspective view showing a tanker moored to the mooring structure constructed in accordance with an embodiment of the present invention;

FIGURES 2-5 show a mooring procedure for use with the mooring structure made in accordance with an embodiment of the present invention; and more particularly,

FIGURE 2 shows a tanker as it approaches the mooring structure;

FIGURE 3 shows the tanker attached to the forward pod located on the forward boom;

FIGURE 4 shows the tanker as it is drawn adjacent the mooring structure;

FIGURE 5 shows the tanker in the final moored position;

FIGURE 6 shows a side view of the mooring structure constructed in accordance with an embodiment of the present invention positioned for rotatable movement about a fixed storage tank;

FIGURE 7 shows a top view of the mooring structure taken along lines 7-7 in FIGURE 6;

FIGURE 8 shows an enlarged fragmentary, sectional view of a portion of the after or first boom taken along lines 8-8 in FIGURE 7;

FIGURE 9 shows an enlarged fragmentary view of a damping means arrangement constructed in accordance with an embodiment of the present invention;

FIGURE 10 shows an enlarged fragmentary view of the damping means shown in FIGURE 9;

FIGURE 11 shows a fragmentary view of the positioning of the mooring structure constructed in accordance with an em bodiment of the present invention about a portion of a fixed storage facility; and

FIGURES l2 and 13 illustrate the damping effect resulting from a mooring structure constructed in accordance with an embodiment of the present invention as compared to an undamped system.

Referring initially to FIGURE 1, there is shown tanker l0 moored to structure 20 which in turn is rotatably positioned about storage facility 21. Mooring structure 20 includes a forward or second boom 22 and an after or first boom 24.

Booms 22 and 24, as seen in FIGURES 6 and 7 are attached to a hollow, cylindrically shaped member 26. After boom 24 comprises spaced tubular members 28, 30, 32 which extend away from cylinder 26 and converge inwardly at after pod 40. Tubular rib members 34 join members 28, 30, 32, as seen in FIGURE 8, to form a triangular shaped member. Tubular member 30 is positioned above the surface of the water upon which structure 20 floats. A plurality of fenders 42 are attached to members 30 and 32 and are spaced along the length of after boom 24 as seen in FIGURES 7 and 8 to prevent direct contact between after boom 24 and a moored ship.

Forward boom 22 includes spaced tubular members 44, 46, 48 which extend awayfrom cylindrical member 26 and converge inwardly to be joined at forward pod 52. Tubular rib members 50, similar to ribs 34, connect members 44, 46 and 48. Member 46 is spaced from and positioned vertically above tubular member 48 with these two members being connected by rib member 50. The result is that tubular members 46, 48 of forward boom 22 are substantially axially aligned with respective tubular members 30, 32 of after boom 24. Although these tubular members are shown as being axially aligned, they could be offset from each other, if desired. Fenders 42, as seen in FIGURE 7, are attached to and extend along the length of members 46, 48 of forward boom 22.

Forward pod 52, as seen in FIGURES l and 7 is offset from the axis which passes through the center lines of fixed storage tank 21 and outboard pod 40 to achieve the desired tanker berthing procedure. The amount of offset of pod 52 can be varied.

A second hollow, cylindrically shaped member 56 is located inside of and spaced from member 26. The second member is positioned about neck 58 which extends upward from a fixed storage facility. A platform and tower for personnel 57 is located on top of neck 56. The inner wall of member 56, which is contiguous to neck 58, is lined with teakwood, lignum vitae or othersuitable material 55. Member 56 is adapted for rotation about neck 58. Perforated plate 64 is welded or attached by suitable means to extend from and about the circumference of outer wall 66 of member 56 while perforated plate 68 is welded or attached by suitable means to extend from and about the circumference of inner wall 70 of member 26.

As seen in FIGURES l and ll, shackles 72 are inserted in the holes in plates 64 and 68. Lines 74 made of nylon or other suitable material connect members 26 and 56 together in a spoke-like arrangement as seen in FIGURES 9-1 1, with the ends of each nylon line being joined to shackle 72 by means of a splice or dead end 76. This spoke-like arrangement assists in damping loads which would otherwise be transmitted to the fixed storage facility.

The damping feature of the present invention is illustrated more fully in FIGURES l2 and 13. In FIGURE 12, there is illustrated a fixed structure 78 which in a conventional mooring system would be joined to a tanker, illustrated at 79, by mooring line 80. Mooring line 80 will sag or stretch as a result of wave, wind or current action. There is provided a system which consists of a mass 79 attached to a permanent or fixed structure 76 by spring 80, the mass oscillating by wave, current or wind action.

FIGURE l3 shows fixed structure 82 and a mass, such as a tanker illustrated at 84. Instead of having a mooring line connecting the mass to the fixed structure directly as in FIGURE 12, mooring line 86 connects the tanker to a movable member illustrated at 88 which corresponds to floating mooring structure 20 of the present invention. Member 88 is elastically connected to the fixed structure by spring means 90 which corresponds to the spoke-like nylon line arrangement seen in FIGURES 9-l l inclusive. The system of FIGURE 13 produces a softer spring action than is available in the system illustrated in FIGURE 12 and, consequently, a greater degree of damping occurs with the floating system of FIGURE 13.

Further, the system of the present invention has the ability to change its natural frequency by a change of ballast in the mooring structure. This damping can be accomplished by the addition or removal of liquid such as oil or water to various compartments in pods 40, 52 and other members such as those which comprise booms 22 and 24. With this ability to change the ballast in the structure, thereby affecting the natural frequency of the mooring device, the difference in period between a tanker and booms 22, 24 can be reduced. As a result, not only will the oscillation of each of the mooring structure and the tanker be of the same order of magnitude but the phase relationship between the two will also be reduced. By utilizing this mechanical change in frequency of the mooring structure, the relative motions between the loading pod and the tanker may be reduced significantly thereby allowing a loading operation to take place in poor weather conditions.

ln a berthing procedure, tankship would head into the predominant resistance characteristic generated by wind and/or sea conditions at a slow speed but sufficient enough to permit steerage way for ship 10. Mooring structure would be rotated as required by means of thruster 92, preferably located on the after pod 40, although thruster means could be located on the forward pod or both pods if desired. The mooring structure is powered to a position so that it is disposed as seen in FIGURE 2 and the distance between the ship's motion and the center line of fixed storage structure is kept at a specified distance such as 200 feet.

Ship 10 is maintained in the position seen in FIGURE 3 and mooring lines 96, 98, 100 secure ship 10 to the forward and after pods 52, 40. During this phase of the mooring procedure, thruster 92 is actuated as necessary to maintain the position of the mooring structure relative to tank 10.

Subsequently, as seen in FIGURE 4, ship 10 is stopped or slowed so that the forces exerted by the wind and sea cause the ship to drift to the leeward or, if necessary, ship 10 may be powered aft thereby tightening the lines from the bow to forward pod 52. Thruster 92 can be actuated during this time to move after boom 24 toward the ship until it reaches a position shown in FIGURE 4 or ship 10 can be moved aft toward after boom 24. The thruster can be electric or engine driven or it can be a fluid moment transfer device.

As soon as boom 24 reaches the position shown in FIGURES 4 and 5, loading arms or hoses, not shown, can be connected and ship 10 can take on the product and discharge ballast as required. The liquid product and ballast can be transmitted through the tubular members of the booms 22, 24 and members 26, 56 as required by suitable valve means and the like. This has not been shown as it is within the purview of one skilled in the art to employ available means to transmit the product and ballast to and from ship 10 and facility 21.

Upon completion of the loading operation, ship 10 can be removed from mooring structure 24 by casting off all lines, and allowing the ship to go dead slow astern while boom 24 is moved slightly away from ship 10 by thruster means 92. The ship backs out of its berth to a reasonable distance and proceeds upon its course.

Although one embodiment of applicants mooring structure has been shown, it is appreciated that other constructions can be used. For example, rib members 50 and 34 could be eliminated and tubular members, such as 28, 30, 32, 46, and 48, could be made of different materials.

Moreover, other damping means could be used to furnish the desired elasticity between mooring structure 20 and storage tank 21.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

lclaim:

l. A floatable mooring structure adapted for use with a fixed facility, said structure comprising:

a first floatable mooring member adapted to be positioned for rotation about and contiguous to said fixed facility;

a second floatable mooring member disposed about and spaced from said first floatable member; and

said first and second floatable members being elastically connected together by damping means.

2. A structure in accordance with Claim 1, wherein said second mooring member includes a forward boom and an after boom which are substantially fixed relative to each other; and

said booms being joined to and extending away in different directions, from said second mooring member.

3. A mooring structure adapted for use with a fixed facility, said structure comprising:

a first mooring member adapted to be positioned for rotation about said facility;

a second mooring member disposed about and spaced from said first member;

said second mooring member including a eylindrically shaped member;

said second member having a forward boom and an after boom which are substantially fixed relative to each other;

tubular members extending away from said eylindrically shaped member in a first direction to comprise said after boom;

tubular members extending away from said eylindrically shaped member in a second direction to comprise said forward boom; and

damping means for connecting said first mooring member to said second mooring member.

4. A floatable mooring structure adapted for use with a facility, said structure comprising:

a first floatable mooring member adapted to be positioned for rotation about said facility;

a second floatable mooring member disposed from said first member;

resilient dampingmeans for elastically connecting said first mooring member to said second mooring member; and ballast means for adjusting the damping characteristics of said mooring structure. 5. A floatable mooring structure adapted for use with a fixed facility, said structure comprising:

a first floatable mooring member adapted to be positioned for rotation about said facility; a second floatable mooring member disposed about and spaced from said first member; said first mooring member being cylindrically shaped and adapted to be positioned for rotation about said faciliy; line damping means for elastically connecting said first mooring member to said second mooring member; and said second mooring member including a forward and after boom joined to said second mooring member and extending away from said second member in different directions. 6. A mooring structure in accordance with claim 3, wherein said after boom includes an after pod disposed at the end of said after boom furthest from said cylindrically shaped member.

7. A mooring structure in accordance with claim 6, wherein said after pod has a powered thruster means for providing radial orientation of said mooring structure about said storage facility.

8. A mooring structure in accordance with claim 6, wherein said forward boom includes a forward pod disposed at the end of said forward boom furthest from said cylindrically shaped member.

9. A floatable mooring structure adapted for use with a storage facility, said structure comprising:

a first member disposed about said storage facility and adapted for rotation about said storage facility;

a second member spaced from and about said first member, said second member having a forward boom and an after boom extending outwardly from said second member;

said forward and after booms being substantially fixed relative to each other;

damping means connecting said first and second members;

a forward pod located at the end of said forward boom furthest from said second member; and

an after pod located at the end of said after boom furthest from said second member, said forward boom being offset from said after boom.

10. A floatable mooring structure adapted for use with a storage facility, said structure comprising:

aftrs tmember-disposed about said storage facility and adapted for rotation about said storage facility;

a second member spaced from and about said first member, said second member having a forward boom and anafter boom extending outwardly from said second member;

damping means connecting said first and second members;

a forward pod located at the end of said forward boom furthest from said second member;

an after pod located at the end of said after boom furthest from said second member, said forward boom being offset from said after boom;

said first member being cylindrically shaped and adapted to be positioned and rotated about said storage facility;

said second member including a cylindrically shaped portion from which said forward and after booms extend, said cylindrically shaped portion extending about and spaced from said first cylindrically shaped member; and

line means arranged in a spoke-like manner in the space between and connecting together said first cylindrically shaped member and said cylindrically shaped portion 11. A floatable mooring structure in accordance with claim 10, further including a thruster means attached to said second member for providing radial orientation of said mooring structure about said storage facility.

12. The method of mooring a vessel about a fixed storage facility having a mooring structure adapted for rotation positioned about said facility, said mooring structure comprising a forward boom having a forward pod at the end of said forward boom, an after boom having an after pod located on said after boom, and means for radially orienting said mooring structure about said storage facility, said method including the steps of:

actuating said radial orienting means to move said forward pod near said vessel;

connecting said vessel and forward pod together;

moving said mooring structure toward said vessel whereby said after pod is moved contiguous to said vessel; and

further connecting said vessel and mooring structure together whereby said vessel is held in a substantially fixed position relative to said storage facility,

13. The method of claim 12 further including the step of changing the natural frequency of said structure during said mooring operation by changing the amount of ballast in said mooring structure.

14, A mooring structure in accordance with claim 5, wherein said line damping means comprises nylon line means.

15. A floatable mooring structure in accordance with claim 10, wherein said line means comprises nylon line means. 

